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INTRODUCTORY BIOCHEMISTRY
Bio. 28
Second Midterm Examination
March 24, 2005
Name
Make sure that your name is on every page. This is the only way we have of
matching you with your exam if the pages get separated. Please work
independently. Read each question carefully before answering. Unless
otherwise indicated, there is only one correct answer for each multiple choice
question. Points are indicated by the question within brackets [].
Page 1 total __________/6
Page 2 total __________/18
Page 3 total __________/20
Page 4 total __________/23
Page 5 total __________/16
Page 6 total __________/17
Exam total ___________/100
Name ____________________________________
Given the following information:
pyruvate + 2 H+ + 2 e– → lactate
E’o = –0.185 V
lipoic acid + 2 H+ + 2 e– → dihydrolipoic acid
E’o = –0.29 V
F = 96.5 kJ/mol-V
1. [1] ΔE’o for the reaction: pyruvate + dihydrolipoic acid → lactate + lipoic acid is
a)
b)
c)
d)
e)
0.475 V
–0.475 V
0.105 V
– 0.105 V
none of the above
2. [1] ΔG’o for the above reaction is
a) 45.84 kJ/mol
b) –45.84 kJ/mol
c) 10.13 kJ/mol
d) –10.13 kJ/mol
e) 20.27 kJ/mol
f) –20.27 kJ/mol
Questions 3-9 are omitted
Given the following list of enzymes:
a) α-ketoglutarate dehydrogenase
b) fumarase
c) malate dehydrogenase
d) succinate dehydrogenase
e) aconitase
f) citrate synthase
g) isocitrate dehydrogenase
h) succinyl-CoA synthetase
10. [3] Which of the above enzymes produce(s) NADH? _________________
11. [1] Which of the above enzymes produce(s) FADH2? _________________
12. [2] Which of the above enzymes produce(s) CO2? _______________
13. [1] Which of the above enzymes contain(s) lipoic acid as a cofactor?
_________
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Name ____________________________________
14. [2] What is the order of the enzymes in the citric acid cycle, beginning with
the enzyme that produces ATP or GTP? (must be entirely correct to receive
credit) _______________________________________________
15. [2] Name an enzyme that catalyzes an anaplerotic reaction, and name its
cofactor. _________________________ _________________________
16. [2] Name two enzymes that occur in the glyoxylate cycle but are not members
of the citric acid cycle. ____________________ ________________________
17. [14] In the mitochondrial electron transport chain, which (one or more) of the
macromolecular complexes (I, II, III, IV):
A. Contain(s) Fe/S clusters? ______________
B. Contain(s) essential copper ions? __________
C. Contain(s) bound flavin cofactors? __________
D. Interact(s) with cytochrome c? __________
E. Interact(s) with ubiquinone? __________
F. Contain(s) heme molecules? __________
18. [1] How many catalytic adenylate-binding sites does ATP synthase contain?
______
19. [1] How many protons must be translocated across the mitochondrial inner
membrane for each ATP synthesized? ______
Question 20 is omitted
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Name ____________________________________
CH2OPO3H2|
C=O
|
H-C-OH
|
H-C-OH
|
CH2OPO3H221. [1] Indicate with (an) asterisk(s) (*) which carbon atom of the above
compound reacts with CO2 in the Calvin cycle.
22. [1] Identify an alternative molecule that this compound reacts with.
__________________
23. [11] In photosynthetic carbon dioxide fixation carried out by the enzymes of
the Calvin cycle, three molecules of carbon dioxide condense with _________
molecule(s) of the sugar-phosphate substrate
______________________________ in a reaction catalyzed by the enzyme
______________________________. The actions of other enzymes of the
Calvin cycle ultimately regenerate the sugar-phosphate substrate molecule(s)
and yield __________ molecule(s) of the sugar phosphate product
______________________________. The production of this amount of product
by this process requires the energy derived from the hydrolysis of __________
molecule(s) of ______________________________ as well as the reducing
equivalents derived from the oxidation of __________ molecule(s) of
______________________________. In plants that use the C4 process to raise
the intracellular concentration of carbon dioxide, the production of the same
amount of product requires additional energy that is derived from the hydrolysis
of __________ additional molecules of ______________________________.
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Name ____________________________________
24. [12] In the gluconeogenic pathway from pyruvate to glucose 6-phosphate, a
net total of _____ phosphoanhydride bonds are consumed per molecule of
glucose 6-phosphate formed. In contrast, a net total of _____ phosphoanhydride
bonds are formed in the reverse glycolytic formation of pyruvate, per glucose 6phosphate. Thus, a “futile cycle” between pyruvate and glucose 6-phosphate
would result in the net consumption of _____ phosphoanhydride bonds per
molecule of glucose 6-phosphate cycled. One mechanism to control futile cycling
is the reciprocal regulation of glycolysis and gluconeogenesis by the action of the
small molecule __________________________ , which inhibits the enzyme
_____________________ and stimulates the enzyme ____________________.
Given a choice of the following compounds:
a)
b)
c)
d)
e)
glucose 1-phosphate
glucose 6-phosphate
glucose
UDP-glucose
ADP-glucose
25. [1] The product of starch phosphorylase is _____.
26. [1] The product of glycogen phosphorylase is ____.
Question 27 is omitted
28. [1] Glucose units are added to a growing molecule of glycogen from ____.
29. [1] _____ is a product of the debranching enzyme.
30. [3] The interconversion of __-glycerol 3-phosphate and __-glyceraldehyde 3phosphate occurs via the achiral intermediate ___________________________.
Given the following list of molecules:
a) Malic acid
b) Maleic acid
c) Malonyl-CoA
d) Mevalonic acid
e) Methylmalonyl-CoA
f) Myristic acid
31. [1] Which one is a precursor of fatty acids? _____
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Name ____________________________________
32. [1] Which one is a precursor of cholesterol? _____
33. [1] Which one is an intermediate in the citric acid cycle? _____
Question 34 is omitted
35. [1] Which one is an intermediate in catabolism of odd-numbered fatty acids?
_____
36. [3] In the coordinated regulation of fatty acid synthesis and catabolism, the
fatty acid precursor _______________________ is an inhibitor of the ratecontrolling enzyme of fatty acid catabolism, ____________________________,
and synthesis of this fatty acid precursor is inhibited by ___________________.
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Name ____________________________________
Indicate whether each of the following statements is true or false:
37. [1] T
F
Catabolism of oleic acid yields less ATP per mol than that of
stearic acid.
38. [1] T
F
Catabolism of palmitic acid yields less ATP per mol than that of
stearic acid.
39. [1] T
F
Hydroxymethylglutaryl-CoA is a precursor of both ketone bodies
and cholesterol.
40. [8] Some amino acids can be formed in one step by transamination of a
precursor that has the same carbon skeleton and is a common metabolite such
as an intermediate in glycolysis, the citric acid cycle, or the glyoxylate cycle.
Identify 4 such amino acids and indicate their non-amino precursors.
Non-amino precursor
Amino acid
____________________
____________________
____________________
____________________
____________________
____________________
____________________
____________________
41. [1] Amino acids which are considered ketogenic are degraded to which of the
following:
a)
b)
c)
d)
fumarate
pyruvate
acetyl-CoA
α-ketoglutarate
42. [5] In the urea cycle, ammonia is activated by conversion to
______________________. This compound then condenses with the nonprotein
amino acid _________________________. These two reactions occur in the
(subcellular location) _________________________. The product of this
condensation, ________________________, is transported to another
subcellular location where it condenses with __________________________ to
form argininosuccinate, which is then decomposed in several steps to yield urea.
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